1,2-Dichloroethane → N-benzylsulfanylcarbonylmethyl-6-(3,6-dihydroxy-3H-xanthen-9-yl)-isophthalamic acid

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Reaction Steps

To a solution of 13 (0.424 g, 0.92 mmol) in dry THF was added EDC (0.176 g, 0.92 mmol) and HOBt (0.14 g, 0.92 mmol). The solution was stirred for 30 minutes under ice-cold conditions, followed by addition of 8 (0.2523 g, 1.16 mmol) dissolved in minimal amount of DMF. The resulting solution was stirred further for 6 hours at RT. Upon removal of the solvent in vacuo, the residue was taken into ethyl acetate and washed with 1 N HCl (2×30 ml), water (2×30 ml) and brine (2×30 ml). The organic layer was dried over anhydrous Na2SO4 and concentrated under reduced pressure to afford a crude mixture, which was further purified by flash chromatography (silica gel, dichloromethane/methanol=9:1) to afford 2 (0.32 g, 56%). 1H-NMR (300 MHz, CDCl3) δ 8.52 (s, 1H), 8.22 (d, J=8.04 Hz, 1H), 7.25-7.21 (m, 6H), 7.12-7.09 (m, 2H), 6.81-6.75 (m, 4H), 4.39 (d, J=5.61 Hz, 2H), 4.15 (s, 2H), 2.3 (s, 6H). 3C-NMR (60 MHz, DMSO) δ 196.52, 168.78, 168.37, 165.84, 155.31, 152.20, 151.42, 136.72, 134.08, 129.58, 127.74, 127.50, 127.33, 126.45,125.61, 124.50, 123.91, 115.53, 110.46, 82.09, 49.48, 32.90, 20.98. MS (ESI): m/z 623.9 [(M+1)]+.

Provenance & Evidence